Related articles

Biometric scanners for passports came in during 2005, which allowed an additional facial recognition element to prevent fraudulent use and terrorism.

By smiling, the facial recognition software may not recognise the person’s face.

A Home Office spokesman told the BBC: "When the mouth is open it can make it difficult for facial recognition technology to work effectively."

User Dan Holliday expanded why this doesn’t work on Quora: “This is because biometric facial scans typically identify 14 - 20 points on your face (edge of nose, eyes, lips, etc.) the position of your face shifts those points and it may cause difficulty in identifying who you are.

“Because of this, the biometric system works best if you maintain a placid, casual look (neither frowning nor smiling).”